A general procedure has been developed to predict the vapor-liquid equilibria (VLE) of solvent/copolymer systems with the Panayiotou and Vera equation of state (PV-EOS), using binary interaction parameters deduced from homopolymer VLE data. Mixing rules are proposed for the PV-EOS pure-component parameters and homopolymer-solvent binary interaction parameters in order to predict solvent solubilities in copolymer systems. This methodology has been evaluated with VLE data acquired in this study for water, methanol, and methyl acetate in poly(vinyl acetate), poly(vinyl alcohol), and a copolymer comprised of these two homopolymers containing 88% (molar) poly(vinyl alcohol) repeat units. The predictions from the PV-EOS of the copolymer VLE are in excellent agreement with our experimental data.